Differential and variable stiffness orthosis design with adjustment methods, monitoring and intelligence

ABSTRACT

An assistive ankle foot orthosis is described. The AFO has a tubular vertical member arranged laterally to a user&#39;s limb. The member carries a rotational bearing and a rotational element such as a pulley. The pulley is connected to a footplate. The footplate provides joint movement assistance or resistance to the user upon rotation of the pulley. The pulley is coupled to one or more springs that provide counter-rotational resistance to pulley movement, thereby storing, and then returning, rotational force during certain foot movements. The spring can include a leaf spring arranged inside the member, the stiffness of which can be manually, automatically or dynamically adjusted by movement of the device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/515,300 entitled Differential and Variable Stiffness Orthosis DesignWith Adjustment Methods, Monitoring and Intelligence“, filed on Oct. 29,2021, which claims priority to U.S. Provisional Application 63/107,275entitled “Differential and Variable Stiffness Orthosis Design WithAdjustment Methods, Monitoring and Intelligence”, filed on Oct. 29,2020, and U.S. Provisional Application 63/215,336 entitled “ParallelElastic Leaf Spring for Cable-Actuated Lower Extremity Exoskeleton”,filed on Jun. 25, 2021, the entire contents of which are incorporated intheir entirety herein by reference.

STATEMENT CONCERNING FEDERALLY-FUNDED RESEARCH

This invention was made with government support under Grant No.1R15HD099664 awarded by the National Institutes of Health. Thegovernment may have certain rights in the invention.

BACKGROUND

A number of injuries or conditions can lead to disorders that affectmuscle control. Individuals with muscle control disorders frequentlyexperience a downward trend of reduced physical activity and worseningof gait function leading to a permanent decline in ambulatory ability.Upper- or lower-extremity orthoses, including ankle foot orthoses(AFOs), are commonly prescribed for individuals who suffer from suchmuscle control disorders, or other impairments, as from stroke,incomplete spinal cord injury and cerebral palsy. These devices providemobility enhancement by applying assistive joint torque through the gaitcycle. Existing devices use a variety of design approaches to accomplishthis fundamental aim. These devices may include Bowden cable actuation,direct-drive shank mounted motors, fabric shank interfaces, bilateralcarbon fiber frames, and lateral lower leg structures. Certain devicescan also be used for training or strengthening aids, by providing activeresistance during some or all phases of the gait cycle.

AFOs generally include footplates to direct torsional force provided atthe angle toward the ground, or additionally alternatively, to resisttorsional forces imparted by the user's ankle joint. The footplate islocated beneath the user's foot, and between the user's foot and theground, typically on the foot bed of a shoe worn by the user. Inaddition to constituting a force transmitting interface between theuser's foot and the ground, in the case of active devices, the footplate typically carries one or more sensors, such as pressure sensors,which may measure the force being applied to the foot plate or theground by the user of the device. Inventive embodiments below describecertain improvements to passive, quasi-passive and active AFOs.

BRIEF SUMMARY

Embodiments of the invention are directed to a passive or active anklefoot orthosis for assisting with ankle motion, training, rehabilitationand the like. The AFO includes an adjustable tensioning component (e.g.,one or more springs) coupled to a transmission linkage (e.g., a set ofBowden cables, chain, etc., or a tab), and an extended vertical membercoupled to a user's leg via, e.g., a calf cuff. A rotatable bearing ismounted within the member, and is rotatable by a pulley connected to thecables. The bearing is coupled to a footplate, and is rotatable in aplantar direction or a dorsal direction by a wearer. Motion in thesedirections can be assisted or resisted depending on the tension appliedto the cables by the tensioning component. In particular, a tensioningcomponent like a spring can store energy during a portion of the anklerotation, and then the energy as assistive torque when the rotation isreversed. In certain embodiments, the extended vertical member is atubular member having a closed, circumferential cross section, and thebearing is located within the interior space defined by the walls orwall of the tubular member. In preferred embodiments, the verticalmember is arranged laterally with respect to the user's leg, and therotational bearing is arranged such that its axis of rotation iscoincident with the user's ankle. In preferred embodiments describedbelow, tensioning components allow for active or passive tensioning, andthey provide an assistive or resistive torque bias to the footplatecoupled to the rotational bearing.

In one aspect, the invention includes a novel joint orthosis designhaving differential and or variable stiffness via manual, automated, orpassive mechanical adjustment.

In one aspect, the invention is directed to a joint orthosis such as anAFO. The AFO includes a modular, laterally-mounted hinged design, whichis to say, that the point of rotation of the orthosis is lateral to theuser's ankle. The orthosis is comprised of a distal attachmentcomponent, an “upright” component that mounts laterally to the joint(for AFO designs), a hinge mechanism located in line with the joint, anda proximal attachment point. The distal attachment component may includea footplate, and the proximal attachment point may include a calf-cuff.The distal and proximal attachment components may be swapped out fordifference sizes. The upright may be comprised of a rigid carbon fibercircular, oval, rectangular, hexagonal, square or other polygonal tube.The hinge mechanism may incorporate a pulley or cam placed within theupright tube that rotates relative to tube through bearings or bushings.The lateral upright design allows for modularity of the components,minimizes medially-protruding features that cause contact with otherparts of the body, and minimizes anterior or posterior protrudingfeatures that may cause contact with objects in the environment.

In another aspect, the AFO includes differential stiffness springcomponents, for example, linear, compression, rotary, or leaf springs,for the flexion (dorsi extension) and extension (plantar extension)directions. In an assistive configuration, a spring component may beengaged such that the orthosis resists extension during the stance phaseand/or resists flexion during the swing phase. In a trainingconfiguration, these forces may be reversed. For lower-extremity (e.g.,AFO) configurations there may be stance phase spring engagement and/orswing phase spring engagement.

In certain embodiments, AFO's according to the invention exhibitvelocity-dependent stiffness. In such embodiments, the orthosis mayinclude a damping mechanism in the flexor or extensor directions toprovide automatic velocity-dependent stiffness adjustments. Suchembodiments may provide added stiffness when the user is running, forexample. Alternative spring configurations are provided for flexion orextension resistance. For lower-extremity embodiments, the orthosisspring components may be configured to provide extension resistanceduring the stance phase and/or flexion resistance during the swingphase.

AFO's having tensioning springs according to described embodiments haveadjustable flexion and extension equilibrium angles, which are theangles at which the flexion or extension spring component becomesengaged. The springs can be configured so that the equilibrium angle isthe same or different for the flexion and extension directions.

Similarly, some embodiments allow for quick, manual adjustment to theflexion and extension spring stiffnesses through turning a knob,adjusting a slider, lever, or other similar mechanism, without the needof hand or power tools. In additional embodiments, components ormechanisms are included to adjust the flexion or extension springstiffnesses based on joint angle, walking terrain, locomotor condition(walking, running) or speed. Spring stiffness could be adjusted byadding or subtracting linear springs in parallel, pre-loading arotational spring, or adjusting the pivot point on a leaf spring. Insome orthoses of the of the aforementioned mechanical designs,components may or may not include a small actuator (e.g., DC motor) toadjust the spring stiffness, equilibrium angle, or assist/resist mode ofoperation.

In some configurations, mounted within or outside of the upright, thespring components may include linear extension springs, linearcompression springs, leaf springs (e.g., an elastic carbon fiber bar),linear, non-linear, or constant force rotary springs.

In certain embodiments, variable stiffness AFO's include a variety ofsensors and data processing components usable to determine how to adjuststiffness. In such embodiments, the orthosis includes the necessaryelectromechanical and software features (e.g., microprocessor, sensorsand wireless connectivity, cloud server), making it a connected,intelligent orthosis. By tracking sensor data about the user's ankleposition, velocity and acceleration, foot pressure, and the linear andangular acceleration of the AFO itself, such embodiments can provideintelligent recommendations for adjustment of stiffnesses or equilibriumangles. The recommendations may be provided to a user, who may manuallyadjust the device, or to the user's clinical or rehab team, or thedevice may automatically adjust the device to improve device functionand performance.

In one embodiment, a wearable assistive device is described. The devicehas an extended, tubular structural member having a closedcircumferential cross section, a first end and a second end defining along axis through a center of the extended structural member. The deviceincludes an attachment device coupled to the member and extendingmedially from the member, the attachment device configured to secure themember to a limb of a user. The device also has a rotational bearingdisposed within the extended structural member and positioned on thelong axis near the second end of the extended structural member. Thedevice includes a pulley coupled to the rotational bearing, and afootplate dimensioned to support a foot of a wearer of the assistivedevice and coupled to the pulley such that it may rotate with respect tothe long axis of the extended tubular member. The device also has afirst cable having a first end and a second end, the first end coupledto a first spring, the second end coupled to the pulley.

Another embodiment is directed to an alternative wearable assistivedevice. The device has an extended, hollow, tubular structural memberhaving a closed circumferential cross section, a first end and a secondend defining a long axis through a center of the extended structuralmember. The device also has an attachment device coupled to the memberand extending medially from the member, the attachment device configuredto secure the member to a limb of a user. There is a rotational bearingdisposed within the extended structural member and positioned on thelong axis near the second end of the extended structural member, and arotational element coupled to the rotational bearing. The deviceincludes a footplate dimensioned to support a foot of a wearer of theassistive device and coupled to the rotational element such that it mayrotate with respect to the long axis of the extended tubular member. Thedevice also includes a leaf spring arranged within the hollow, tubularmember, and a cable having a first end and a second end, the first endcoupled to the leaf spring and the second end coupled to the rotationalelement.

AFOs according to inventive embodiments have certain advantages, whichare also applicable to assistive orthoses for other joints. For example,the embodiments described below improve the ability of an individual tofit a device and perform self-calibration or customization of the amountand angle of joint support (i.e., stiffness) without the need to visit acertified orthoptist. The self-adjustability of the device permits auser to dial-in different support quantities or change the angle as theuser progresses throughout a rehabilitation program, or encountersdifferent sorts of walking terrain (i.e., flat areas versus hillyareas). Additionally, inventive embodiments accommodate interchangeablecomponents (e.g., springs, vertical members or footplates) that can beswapped out for larger/smaller sizes. Inventive embodiments provide theoption for user and device monitoring and are usable to create aconnected device that can be used for telerehab or telemedicine.Additionally, the device modifications described herein are usable tooptimize performance across different ambulatory conditions. Additionaladvantageous will become clear upon consideration of the detaileddescription of the preferred embodiments taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein constitute part of this specification andincludes exemplary embodiments of the present invention which may beembodied in various forms. It is to be understood that in someinstances, various aspects of the invention may be shown exaggerated orenlarged to facilitate an understanding of the invention. Therefore,drawings may not be to scale.

FIG. 1 depicts one embodiment of a novel ankle foot orthosis withinterchangeable components, and differential and variable springstiffness (top). Potential ankle pulley component designs (bottom).

FIG. 2 depicts equilibrium angle and potential linear, stiffening, orsoftening spring force responses.

FIG. 3 depicts different spring designs: leaf (3A), internal compression(3C), and rotary (3B).

FIG. 4 depicts intelligent AFO components (microprocessor, battery,connectivity, sensors) and optional DC motor for adjusting leaf springstiffness.

FIG. 5 is schematic depiction of data flow for an intelligent AFOdesign.

FIG. 6 depicts a manual adjustment knob mounted to the main hinge pulleythat adjusts equilibrium angle.

FIG. 7A depicts a passive spring-based mechanism for dynamic leaf springpivot adjustment.

FIG. 7B depicts a passive spring-based mechanism for dynamic leaf springpivot adjustment having a different orientation.

FIG. 8 depicts a hydraulic-piston-based mechanism for dynamic leafspring pivot adjustment.

FIG. 9 depicts a powered AFO with a parallel mounted spring foradditional assistance.

FIG. 10 depicts an alternative embodiment of a powered or passive AFOhaving an internally mounted leaf spring.

FIG. 11 depicts the operation and torque profile of the embodiment ofFIG. 10 .

FIG. 12 depicts an AFO having a pair of internally mounted leaf springs.

FIG. 13 depicts an alternative view of the passive AFO of FIG. 12 .

FIG. 14 depicts an equilibrium adjustment mechanism usable with theembodiments described herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The described features, advantages, and characteristics may be combinedin any suitable manner in one or more embodiments. One skilled in therelevant art will recognize that the invention may be practiced withoutone or more of the specific features or advantages of a particularembodiment. In other instances, additional features and advantages maybe recognized in certain embodiments that may not be present in allembodiments.

Reference throughout this specification to “one embodiment,” “anembodiment,” or similar language means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment. Thus appearances of the phrase“in one embodiment,” “in an embodiment,” and similar language throughoutthis specification may, but do not necessarily, all refer to the sameembodiment. References to “users” refer generally to individualsaccessing a particular computing device or resource, to an externalcomputing device accessing a particular computing device or resource, orto various processes executing in any combination of hardware, software,or firmware that access a particular computing device or resource.Similarly, references to a “server” refer generally to a computingdevice acting as a server, or processes executing in any combination ofhardware, software, or firmware that access control access to aparticular computing device or resource.

For purposes of description herein, the terms “upper,” “lower,” “right,”“left,” “rear,” “front,” “vertical,”, “upright”, “horizontal,” andderivatives thereof shall relate to the embodiment of the invention asoriented in FIG. 1 . However, it is to be understood that the inventionmay assume various alternative orientations, except where expresslyspecified to the contrary. It is also to be understood that the specificdevices and processes illustrated in the attached drawings, anddescribed in the following specification are simply exemplary examplesof the inventive concepts defined in the appended claims. Hence,specific dimensions and other physical characteristics relating to theexamples disclosed herein are not to be considered as limiting, unlessthe claims expressly state otherwise.

As required, detailed examples of the present invention are disclosedherein. However, it is to be understood that the disclosed examples aremerely exemplary of the invention that may be embodied in various andalternative forms. The figures are not necessarily to a detailed designand some schematics may be exaggerated or minimized to show functionoverview. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention.

In this document, relational terms, such as first and second, top andbottom, and the like, are used solely to distinguish one entity oraction from another entity or action, without necessarily requiring orimplying any actual such relationship or order between such entities oractions. The terms “comprises,” “comprising,” or any other variationthereof, are intended to cover a non-exclusive inclusion, such that aprocess, method, article, or apparatus that comprises a list of elementsdoes not include only those elements but may include other elements notexpressly listed or inherent to such process, method, article, orapparatus. An element preceded by “comprises . . . a” does not, withoutmore constraints, preclude the existence of additional identicalelements in the process, method, article, or apparatus that comprisesthe element.

As used herein, the term “and/or,” when used in a list of two or moreitems, means that any one of the listed items can be employed by itself,or any combination of two or more of the listed items can be employed.For example, if any assembly or composition is described as containingcomponents A, B, and/or C, the assembly or composition can contain Aalone; B alone; C alone; A and B in combination; A and C in combination;B and C in combination; or A, B, and C in combination.

As used herein, the terms “assistance” and “resistance” may be usedinterchangeably to signify the direction of external torque applied to ajoint that may be perceived as augmenting (making a movement easier,assistance) or harder (resistance).

The following disclosure relates to an AFO comprised of a footplatecomponent, an “upright” component that mounts laterally to the lowerlimb, a hinge mechanism located in line with the ankle joint, and a calfattachment point. The footplate is interchangeable and can be swappedout for different sizes. The calf attachment component could be a “calfcuff” or “shin cuff” that incorporates a rigid or semi-rigid shell witha soft (e.g., foam) lining; the calf attachment can be adjust up or downthe limb and be interchanged for different sizes. The upright may becomprised of a rigid carbon fiber circular, oval, rectangular,hexagonal, square or other polygonal tube. The hinge mechanism mayincorporate a pulley, cam, sprocket or a combination of these placedwithin the upright tube that rotates relative to upright throughbearings or bushings. The lateral upright design, quick release featuresand component modularity of the design allows the AFO to grow with achild. In some configurations, mounted within or outside of the upright,the spring components may include linear extension springs, linearcompression springs, leaf springs (e.g., elastic carbon fiber bar),linear, non-linear, or constant force rotary springs. A clutch orengaging/disengaging ratchet may be used to differentially adjust springtiming.

The AFO may include different joint stiffness components (e.g., alinear, compression, rotary, or leaf spring) for the plantar-flexiondirection (pointing toes downward) and the dorsi-flexor direction(pointing toes upward), so that the plantar-flexor direction is stifferthan the dorsi-flexor direction. In an assistive configuration, a springcomponent may be engaged such that the AFO resists extension during thestance phase and/or resists flexion during the swing phase. In aresistive configuration, a spring component may be engaged such that theAFO resists plantar-flexion during the stance phase and/or resistsdorsi-flexor during the swing phase. The AFO may have adjustableplantar-flexor and dorsi-flexor equilibrium angles.

In one embodiment of a quasi-passive novel AFO, a small DC motoractuates a mechanism to adjust the equilibrium angles and/or springstiffnesses in the plantar- and/or dorsi-flexor directions. In anotherconfiguration, the AFO may include knobs, levers, or sliders to easilycustomize and adjust plantar- or dorsi-flexor spring function.

In one embodiment, the intelligent AFO tracks user and device function,automates recommendations for device settings, performs adjustments orinstructs the user how to make adjustments. The device streams use andcompliance information to a cloud-based server for monitoring by theclinician and insurance company.

Referring now to FIG. 1 , there is shown a schematic diagram of avariable tension AFO according to an inventive embodiment. In theembodiment of FIG. 1 an AFO 100 includes a rigid upright member 105.Member 105 is preferably a hollow tubular member formed of carbon fiberor the like, having a square, rectangular, other polygonal, circular orelliptical cross section. Member 105 may have a constant or variablecross section throughout its length. Member 105 includes at a proximalend a first attachment point 110, which receives an attachment device115 such as a calf cuff. Attachment device 115 may alternatively be ashin cuff (pictured at right), or may be an attachment device capable ofsecuring AFO 100 to some other limb or some other portion of the leg. Ina preferred embodiment, attachment device 115 is attached to member 105by a rigid but detachable mechanism, such as fasteners that securedevice 115 to member 105 through non-illustrated fastener holes. Thus,attachment device 115 is replaceable, such that the AFO may beconfigured for users having legs of different sizes. In one embodiment,attachment device 115 may be attached at a plurality of positions alongthe proximal area of member 105 to allow for adjustment of the distancebetween attachment device 115 and rotational bearing 120. Adjusting theposition of cuff 115 with respect to rotational bearing 120 allows theuser to mount AFO to the user's leg such that rotational bearing ispreferably positioned such that its rotational axis is through theuser's ankle. In a preferred embodiment, when worn, the member 105 ofthe AFO is located on the lateral side of a user's leg, and device 115is oriented on member 105 to engage with the leg of the user to positionmember 105 on a medial side of the user's leg. That is to say, device115 may extends medially from member 105.

AFO 100 also includes a rotational bearing 120, which engages with apulley, cam, sprocket or some other rotational hinge element 125 suchthat rotational hinge element 125 is secured to and may rotate withrespect to member 105. Preferably, the member 105 has a long axis thatpasses through and is perpendicular to an axis of rotation of bearing120. In one embodiment rotational element 125 is a circular pulley thatis mounted to rotational bearing 120 such that its lateral and medialsides are both located within the perimeter walls of the member 105. Insuch cases, member 105 may include one or more apertures (130) allowingpassage of a portion of the pulley sheave through the member 105.Additionally, pulley 125 may include a component 127 of its sheave toselectively render the perimeter of the sheave discontinuous so as tofacilitate installation of the pulley 125 into member 105 before it issecured to bearing 120. Component 127 may be, for example, a removableportion of the sheave, or a translating or swinging gate that opens agap in the sheave. In the illustrated arrangement, the rotationalbearing, and therefore the pulley, is supported on both ends by walls ofthe tubular member 105, which preferably is made of a stiff materiallike carbon fiber. This gives the pulley bilateral support, which isuseful to prevent out of plane deflection of the pulley when the pulleyis being actuated by cables, from either the passive spring components,or when used with active drive cables. Co-pending, co-owned U.S. patentapplication Ser. No. 17/343628 entitled “CABLE-ACTUATED,KINETICALLY-BALANCED, PARALLEL TORQUE TRANSFER EXOSKELETON JOINTACTUATOR WITH OR WITHOUT STRAIN SENSING” describes acceptable, exemplaryconfigurations of AFOs having vertical members and pulleys which areusable in conjunction with embodiments described herein. That referenceis incorporated herein in its entirety.

The AFO 100 of FIG. 1 also includes a footplate or insole bracket 130attached to rotational element 125. The footplate 130 extends medially,and is configured and arranged to engage with the bottom of a user'sfoot when the AFO is worn. Footplate 130 may provide rotational force(i.e., torque) to a user's foot, tending to assist or resist ankleflexion or extension, when torque is applied to pulley 125. Footplate130 is detachable from pulley 125, e.g., by one or more fasteners, suchthat it may be replaced in the event of wear or the desire to change thefootplate's size or shape. Acceptable footplate configurations usablewith the embodiments described herein are described in co-pending,co-owned U.S. patent application Ser. No. 17/365,768 entitled “OPTIMIZEDANKLE EXOSKELETON FOOT PLATE FUNCTION AND GEOMETRY”, the entirety ofwhich is incorporated herein by reference.

AFO 100 includes a bias and tensioning mechanism, 140, which providesassistive or resistive torque to pulley 125 within certain ranges ofrotation of footplate 130. In the embodiment of FIG. 1 , one or morelinear springs (145, 150) are provided that engage a first side and asecond side of the sheave of pulley 125 via cables (128, 129), cord,ribbon, chain or some other tensile force transmission mechanism. As canbe seen, spring 145, depending on its vertical position andconfiguration, will tend to provide extending torque to footplate 130(i.e., to cause plantar extension or resist flexion/dorsi extension),and spring 150, will tend to provide flexion torque to footplate 130(i.e., to cause dorsi extension and resist plantar extension). Thus, inan assistive configuration, the AFO of FIG. 1 includes at least onespring component that may be engaged such that the orthosis resistsextension during the stance phase and/or resists flexion during theswing phase. Providing a pair of springs enables a stance phase springengagement and a swing phase spring engagement.

Springs 145, 150 are mounted to member 105 at one of a plurality ofattachment points along the front or back (i.e., anterior or posterior)surfaces of the member 105. The provision of a plurality of verticallyspaced apart attachment points permit the springs to be biased such thatthe torsional force provided to the pulley 125 may be varied, both interms of magnitude, and in terms of setting the pulley's equilibriumposition for each spring. Some exemplary arrangements along these lineswill now be described.

One function of the arrangement of springs 145, 150 is to set theequilibrium position of footplate 130. The equilibrium position offootplate 130 is the position (i.e., the rotational state) of thefootplate when it is not being acted on by external spring forces (otherthan the forces inherent in non-spring portions of the AFO itself, thatis, the friction of the rotational bearing, and gravity acting on thefootplate, etc.). The footplate will be in its equilibrium positon whenthe AFO device is, for example, suspended, as in when it is held by theupright member. In one embodiment, when the footplate is in itsequilibrium position, the spring forces acting on the pulley are equaland balanced, and the ankle of a user wearing the AFO will receive noextension or flexion assistive or resistive force when the footplate isin the equilibrium position. The positions (along the upright member),and the spring strength (e.g., the spring constant of each spring) maychosen to set the equilibrium positon of the footplate at any angleachievable by the physical constraints of the AFO. For example, if bothsprings equal, and both are anchored to the same position along theupright member, and at equal complimentary positions along the pulleysheaf, the force that each spring exerts on the pulley will be equal.This will be the case regardless of whether or the extent to which thesprings are extended, because the degree of each spring's extension willbe equal. This arrangement will balance the rotational forces acting onthe pulley when the footed is in a horizontal orientation, as shown inFIG. 1 . Again, a user wearing the device when the footplate is in thisposition (i.e., the standing during the stance stage of the gait) willexperience no auxiliary torque.

In another aspect, the AFO has adjustable flexion and extensionequilibrium angles (i.e., a different footplate equilibrium position foreach direction of rotation, set by each spring). Here, the equilibriumangles are the pulley angles or rotation positions at which the flexionor extension spring components become engaged. Referring again to FIG. 1, both springs are associated with the same 0 degree equilibrium angle,and the first spring 145 is engaged upon flexion from 0 degrees, and thesecond spring 150 is engaged upon extension from zero degrees.

Referring still to the operation of the FIG. 1 embodiment, as set forthabove, there is no assistance provided in the stance phase. As the usertransitions through mid-stance to toe-off, the shank rotates forward,the heel comes up, and the foot rocks forward over the toes. In the AFOof FIG. 1 , during this movement, spring 150 will elongate and exertflexion torque on the footplate, tending to return it to equilibriumposition. Such force may be useful to provide flexion assistance to auser's foot as it comes off the ground, as to return it to a levelposition. Such torque may also be helpful as a training aide—to forcethe user to push the foot down with more force to complete the movementprior to toe-off. Similarly, spring 145 may exert extension assistiveforce tending to return the footplate to equilibrium when the user isrotating the footplate up or dorsally. Such force may be helpful inrotating the foot to horizontal after the heel strike phase of the gait.Such force may also be useful as a training aid—to force the user torotate the foot up with more force prior to heel-strike. By adjustingthe spring weight, the user can vary the amount of resistance andassistance provided. By adjusting the spring positions, the user canchange the equilibrium point, and therefore, can vary the points in thegait cycle where resistance and assistance are provided.

Additionally, as will be explained below in reference to FIG. 2 , byadjusting the positions of the springs, and the equilibrium points ofthe springs, the user can create a non-linear stiffening or softeningresponse to the resistance/assistance. This is accomplished by shiftingthe relative equilibrium points of the springs such that they overlap,meaning that one spring will be counteracting the effect of the otherspring during at least some portion of the movement.

In alternative embodiments, the orthosis may have a clutch orengaging/disengaging ratchet mechanism on either the flexion springcomponent or the extension spring component such that it engages ordisengages at different angles.

As noted above, the rotational hinge element may take a number ofacceptable forms. In some configurations, the hinge mechanism may be acircular pulley (constant radius) or cam pulley (non-constant radius)such that the radius may or may not be constant on the flexion orextension rotational directions. In one embodiment, the variation ofradius with angle is different on one side of the pulley versus theother side (such that the sheave does not have symmetry about itscenterline). A cam pulley allows for adjustments to joint stiffness as afunction of the ankle joint angle. In some configurations, the hingemechanism may be a toothed-sprocket that engages other sprockets. Themain hinge component may be comprised of two separate sprockets, one toengage a flexion sprocket and another to engage an extension sprocket.The secondary sprockets would directly or indirectly apply a resistiveor assistive spring force or torque to the main sprocket/hingemechanism.

FIG. 2 shows an example of the application of torsional force by the AFOas shown in FIG. 1 having a 0 degree equilibrium position (i.e., a levelfootplate). As can be seen, at heel strike, the foot is rotated up, indorsi extension (referred to above as flexion). In this position, spring145 is in tension, making the device rotationally stiff, and exerting acounter rotational force in the plantar direction. As the foot rocksforward to the 0 degree equilibrium position, the assistive force iszero. As the foot continues to rock forward toward toe-off, spring 150is in tension, again making the device rotationally stiff, and exertinga counter rotational force in the dorsal direction. After toe off, thefoot again transitions to level (and a zero assistance equilibriumposition) before preparation for the next heel strike.

It will be appreciated that by choosing different spring strengths, themagnitude of the dorsi and plantar resisting forces relative to oneanother can be changed. Additionally, for any pair of spring weights,the equilibrium points can be changed by adjusting the positions of thesprings. As is shown at the bottom of FIG. 2 the net torque provided tothe footplate by the springs can be stiffened or softened throughout themovement by adjusting the positions of the springs. To take one example,suppose that in the 0 degree position shown in FIG. 1 , both springs145, 150 are under tension, but balanced. In this hypothetical, theequilibrium points for the individual springs would be different, butwould be equally disposed on either side of a midline of the pulley,such that both springs are exerting equal and opposite force when thefootplate is level. As the user moves from stance to toe-off, the userexperiences increasing resistance to plantar extension from theelongation of spring 150, and at the same time, decreasing assistancefrom spring 145 as it compresses. Thus, the resistance (and thereforethe assistance that will be provided to return the foot to level aftertoe-off), increases with the angle of the movement. The same would betrue in the opposite direction. During dorsi extension (calleddorsi-flexion in FIG. 2 ), which is rotating the foot up in preparationfor heel strike, spring 145 provides resistance as the foot it rotatedup from equilibrium. At the same time, spring 150 compresses andprovides less assistance. This stiffening response is reflected in the“stiffening response” curve in FIG. 2 . A softening response throughoutthe movement can be achieved by changing the relative equilibrium anglesassociated with the springs, such that the assistive spring becomesengaged, for example, at larger angles.

Alternative arrangements using different sorts of tensioning mechanismsare depicted schematically at FIG. 3 . FIG. 3A shows a first alternativeAFO 305. In AFO 305, a pair of vertically mounted leaf springs 310, 315are arranged on a front and back side of member 105. Springs 310, 315ride on respective pivots 320, 325. Pivots 320, 325 may be fixed, butpreferably are slidingly attached to the front and back sides of member105, for example, in a vertically arranged track, by a rack-and-pinionarrangement, or the like. In such arrangements, pivots may be slidvertically along member 105 and fixed in place. In alternativeembodiments, pivots 320, 325 are attachable to member 105 at a varietyof discrete or a continuum of fixed positions, by fasteners or the like.Preferably, pivots 320, 325 are independently adjustable. In certainembodiments, pivots 320, 325 are rollers or domes, preferably of somelow friction material like polymer. Pivots 320, 325 may be manuallyadjustable, or translatable by some motorized means. As pivots 320, 325are translated upward along member 105 toward the fixed connectionbetween springs 310, 315 and member 105, the springs deflect outwardfrom the member, and the free length of the springs shortens, whichincreases the spring strength. It is contemplated that these variouseffects will be achieved by the user (or the user's clinical team) byvarying the vertical mounting points of the springs, where preferably,the springs themselves (i.e., the spring weights) remain constant. Thatis to say, this adjustability is accomplished without changing outsprings.

Distal ends of springs 310, 315 are connected to tensile forcetransmitting means 128, 129 (e.g., a cable or chain), via pulleysarranged on or in member 105, to exert pulling force on pulley 125. Thecables are routed to engage the distal ends of their respective leafsprings at close to 90 degrees, and preferably, are routed throughmember 105 (through apertures) to engage pulley 125 on the oppositeside. Routing pulleys, as shown, may be provided to accomplish thiscable routing. In certain embodiments, routing pulleys are mounted onrotational bearings arranged in the front and back walls of member 105.

FIG. 3B schematically illustrates an alternative embodiment in which apair of rotary springs 340, 345, are provided that provide counterrotational force at the pulley 125. In cases such as that of FIG. 3B,the rotational springs 340, 345 may be mounted internal to member 105and medially and laterally on the rotational bearing, for example, oneither side of pulley 125. A reinforced ledge or other stoppingstructure may be provided on the interior of member 105 for therotational springs to push against as they are loaded. In certainalternative embodiments, this stop may be rotatable, and in some cases,ratcheting, to preload each spring and to change the equilibrium angleassociated with each spring. Alternatively, the springs themselves maybe rotated with respect to fixed stops.

In an alternative embodiment of FIG. 3B, there is a single rotary springthat is compressed by angular motion in a first direction and extendedby angular motion in a second direction. In such cases, there may be oneor more adjustable stop surfaces that determine the angle at which thespring starts compressing and the angle at which it starts extending.

FIG. 3C schematically illustrates yet another alternative arrangementusing one of more springs that is loaded in compression. The compressionspring arrangement of FIG. 3C has the advantage that a single spring maybe used, where the spring is connected to both force transmission cables126, 127, such that compression of the spring providescounter-rotational assistance as the footplate is rotated in eitherdirection. In alternative embodiment, a second spring, which may be acompression spring, is provided for rotation in the other direction.

Combinations of one or more of the spring arrangements depicted in FIGS.1 and 3 are contemplated and within the scope of the invention.

FIG. 4 schematically depicts an alternative embodiment of an AFOaccording to the invention. The embodiment of FIG. 4 is similar to theembodiment of FIG. 3A in that it uses vertically mounted leaf springs(310, 315) and adjustable pivots (320, 325). However, in the example ofFIG. 4 , a drive mechanism 405 is provided which can translate thepivots 320, 325 vertically along member 105, thereby adjusting the leafspring tension, and the amount of torque delivered to the pulley. Suchan arrangement is useful for allowing the user to choose the level ofstiffness that the AFO provides. In one aspect, drive mechanism includesan actuator such as a DC motor that drives a ball screw in a first orsecond direction, thereby translating a ball nut. The ball nut isconnected by lateral projections to the pivots 320, 325. The lateralprojections pass through slots in the front and back surfaces of member105, and the ball nut may be prevented from rotating with the screw bycontact between the lateral projections and the slot's perimeter. Thus,as the screw rotates the ball nut, and therefore the pivots, translateup and down. Other drive mechanisms capable of reversible lineartranslation are possible, such as cable and pulley, chain and sprocketor rack and pinion arrangements.

In alternative embodiments, each pivot 320, 325 is independentlyvertically translatable, either manually or through one or more of thedrive mechanisms mentioned above. In the case of a mechanized system,this may be accomplished by providing two separate motors.Alternatively, in cases where dynamic or real time adjustability is nota concern, the mechanism that transmits force from the motor to eachpivot may be selectable, such that it can selectively translate onepivot, then another. As is discussed above in relation to FIG. 3 ,having independently adjustable pivots allows the tension being suppliedto the pulley by the springs be independently adjustable. This allowsthe resistance during toe-up and toe-down movements to be independentlyset.

Drive mechanism 405 may be in electronic communication with driveelectronics, which are also shown in FIG. 4 . Drive electronics mayinclude a motor driver, which receives control signals from a manualswitch or a microprocessor/microcontroller. Motor driver may be poweredby a rechargeable battery. Drive electronics may also include amicroprocessor or microcontroller in communication with a datatransceiver, such as a WiFi or Bluetooth or BLE transceiver.Microprocessor/microcontroller may also be in communication with one orsensors. Sensors may include one or more sensors that provide data onthe angular position of the pulley, for example, Hall Effect sensors,IMU, angle encoders or potentiometers. Additional sensors may includeaccelerometers and gyroscopic or other sensors for detecting angularacceleration. Such sensors may be arranged to gather data regarding theacceleration of the AFO as a whole, for example, to determine itsposition in the gait cycle. Specifically, such sensors may detect heelstrike (from rapid deceleration of the AFO) or swing. Such sensors maybe usable to determine whether the user is walking or running, forexample, based on the magnitude of the detected accelerations or thefrequency of sensed heel strikes. Sensors may also include a pressuresensor, like a force sensitive resistor, located on the footplate underthe distal portion of a user's foot, which may gather data reflectingthe pressure being exerted by the user on the footplate.

FIG. 5 is a data flow diagram showing, schematically, the operation ofthe electronic system described above. Onboard sensors may collect usedata, which may include data relating to foot pressure, angulardisplacement of the pulley and/or footplate, and/or angular velocity andacceleration of the pulley or footplate. Additionally, variousaccelerations may be measured, for example, the angular or linearacceleration of the member 105 or some other part of the AFO. Sensordata is provided to an onboard microprocessor, which analyzes andprocesses the provided data to generate data about the performance ofthe device and the activity of the user. For example, the intelligentorthosis system described here may track the number of movements theuser performs in a session or over time. For lower-extremityembodiments, the device may track the number of steps, user walkingspeed, or joint angles. The device may also record and reportperformance for rehabilitation progress tracking. The microprocessor mayalso receive the provided data and determine settings, such as springstiffness and equilibrium angle, on the basis of the received data.

The device may transmit information external to the device (e.g., to theuser) regarding the determined spring stiffness and equilibriumsettings, so that the user can perform a user-directed manual ormotorized adjustment. Alternatively, a microcontroller can providecontrol signal to the actuator, which adjusts the pivots in accordancewith the determined settings. Alternatively or additionally, thedetermined settings and/or the raw or processed sensor data can becommunicated through the transceiver to external computing device suchas a handheld device (in the possession or a user, or member of theuser's medical or training team), or a remote server such as a cloudserver. Either or both of these external computing devices may do theanalysis of the data and determination of the spring settings that isdiscussed above, rather than the onboard microprocessor. In the casewhere the orthosis is monitored via handheld device (smart phone ortablet), the device may encourage use, provide cues, or use gamificationtechniques. Either or both of the handheld or cloud server devices maytransmit adjustment commands to the microprocessor. As an alternative todirect communication (e.g., over WiFi) between the microprocessor andthe cloud server, the handheld device may communicate data to the cloudserver, acting as a conduit between the AFO and the cloud server.

For quasi-powered and intelligent configurations as described above, theonboard microprocessor or a remote, connected device, may instruct theonboard actuator(s) to adjust the stiffnesses or equilibrium angles ofthe spring components. The onboard actuator(s) would then perform theadjustment. The adjustments would be based on a computer algorithm thatdetermines the optimal stiffnesses or equilibrium angles for a givenambulatory condition or speed (e.g., incline, decline, stairs, slow,fast, walking running) based on a foot sensor, angle sensor,accelerometer, or inclinometer in isolation or in combination.

In embodiments, the AFO includes features allowing for quick, manualadjustment (or fine tuning) to the flexion and extension equilibriumangle through turning a knob, adjusting a slider, lever, or othersimilar mechanism, without the need of hand or power tools. In oneexample configuration, turning a knob in one direction would tension thecable that attaches to the flexion-resisting spring at the same time,and by the same amount, as loosening the tension to the cable thatattaches to the extension-resisting spring; turning the knob in theother direction would have the opposite effect. FIG. 6 , for example,shows a pulley 125 having a knob, hub, barrel or sprocket 605, which isselectably rotatable and then rotationally fixable with respect topulley 125. Distal ends of the transmitting means (e.g., cables) arewound around the knob in opposite directions, and fixed to knob 605.Rotation of the knob creates slack in one cable, while increasing thetension in the other cable. This allows for easy adjustment of theequilibrium angle of the footplate attached to the pulley 125. Incertain alternative embodiments, a pair of knobs are provided, aroundeach of which is would one of the cables. In such embodiments, the slackor each cable can be adjusted independently.

While the leaf spring embodiments described above in reference to FIGS.3 and 3A and 4 contemplate externally mounted leaf springs, this is nota requirement. FIG. 7A shows a variable stiffness AFO having a leafspring that is internal to the tubular upright member 105. The AFO ofFIG. 7A, like those discussed above, has a hollow, tubular uprightmember 105. A stiffening component, in the case of FIG. 7A, a leafspring 705 is located within the member 105, and is fixedly oradjustably mounted to an interior surface of member at a proximal orfirst end 710. A distal end 715 of leaf spring 705 is attached to aforce transmission mechanism (e.g., a cable, chain, etc.), which isattached to pulley 125. The leaf spring 705, when deflected from itsequilibrium position, pulls on the cable, exerting rotational force onthe pulley 125 tending to rotate the attached footplate 130 in adownward or plantar extension direction. Thus, the footplate is rotatedup, in dorsi extension as during a preparation for heel strike, thecable flexes the leaf spring, which exerts a resistive force on thepulley, which will tend to return the foot plate to a level position.This stiffens the device during the toe-up, heel-down movement. Flippingthe orientation of the leaf spring, the direction of the cable, and theattachment point on the pulley reverses the application of the springforce, creating resistance when the footplate is rotated down. A pair ofleaf springs, arranged on opposite interior walls (i.e., front and backwalls) of the tubular member may be used to provide stiffening duringrotation in both directions.

The extent of the stiffening provided by leaf spring 705 may be adjustedby vertical movement of a translatable pivot 720 on which leaf spring705 rides. Moving the pivot 720 up lengthens the free distal portion ofthe leaf spring, thereby making it less stiff, while moving the pivotdown shortens the leaf spring's free distal portion, thereby making itmore stiff. In one embodiment, the vertical position of pivot 720 may bemanually adjusted to vary the amount of stiffness imparted to the AFO bythe leaf spring. Alternatively, a mechanized means for adjusting theposition of the pivot may be provided, such as those discussed above inreference to FIG. 4 .

Thus far, embodiments that are manually adjustable and adjustable via amotorized actuator have been described. The embodiment of FIG. 7 ,however, provides for a fully-passive (i.e., not powered) but dynamicleaf spring pivot point adjustment. The dynamic pivot point adjustmentmechanism may incorporate a mass-spring system that changes positionbased on the motion of the user. For example, in a lower-extremityconfiguration, the mass-spring system may extend downward uponheel-strike, lowering the pivot point and automatically adjusting theleaf spring stiffness. Larger accelerations caused by more-forcefulheel-strikes (e.g., caused by running) would extend the pivot pointdownward to increase leaf spring stiffness.

In this alternative embodiment, including optional components alsoillustrated in FIG. 7A, the AFO can be dynamically adjusted in terms ofstiffness without the need for a mechanized or active driving mechanismlike a motor. Such embodiments are useful for providing variable levelsof assistance or resistance to the user, for example, during differentstages of the gait cycle, or when the user is engaged in running versuswalking. In an alternative embodiment, pivot 720 is attached to a spring725, which exerts upward force on pivot 720, tending to translate pivot720 in an upward direction until the spring force is balanced by theweight of the pivot. During a heel strike, the AFO (including the springmounting point) experiences a sudden deceleration of its velocity in thedownward direction. The AFO stops suddenly, but the pivot continues tomove down, momentarily overcoming the spring force. In its new position,the pivot effectively shortens the free end of the leaf spring,increasing its strength and the resulting resistance it provides tocertain ankle movements (in the case of FIG. 7A, the resistance toplantar extension movements is increased).

FIG. 7A illustrates a single leaf spring creating resistance to dorsiextension, and having a pivot point that can be dynamically adjustedupward and downward through the use of the device. It is contemplatedthat the mechanism shown in FIG. 7A can flipped, so that it providesresistance to plantar extension. Such an embodiment is illustrated inFIG. 7B. In this embodiment, the leaf spring is mounted to a back(posterior) wall of the tubular member, where in the FIG. 7A embodiment,a single spring is mounted to the front (anterior) wall of the tubularmember. In the FIG. 7B embodiment, at heel strike, the pivot moves downby the sudden deceleration of the AFO. As the user moves throughmid-stance to toe-off, the heel comes up, and footplate rotates down.This pulls against the leaf spring which is now shortened against thepivot, so it is stiffer. During swing, the foot rotates back to level,assisted by the stored energy in the spring, and then to toe-up inpreparation for the next heel strike. As this happens, the leaf springis relaxing, and pivot will tend to translate up, softening theassistance.

It should be appreciated that both mechanisms depicted in FIGS. 7A and7B may be combined in the same AFO, similar to the arrangement depictedin FIG. 3A, but with the leaf springs internal to the tubular member.

Another passive yet dynamic mechanism for adjusting leaf spring pivotpoint position includes a hydraulic system to transfer pressure fromunder the foot to a linear slider (or similar) that actuates the pivotpoint. FIG. 8 illustrates such an alternative dynamic AFO with variableresistance/assistance. In the embodiment of FIG. 8 , like that of FIG. 7, a stiffening component, in the case of FIG. 8 , a leaf spring 805 islocated within the member 105, and is fixedly or adjustably mounted toan interior surface of member at a proximal or first end 810. A distalend 815 of leaf spring 805 is attached to a tensile force transmissionmechanism (e.g., a cable, chain, etc.), which is attached to pulley 125.The leaf spring 805, when deflected from its equilibrium position, pullson the cable, exerting rotational force on the pulley 125 tending torotate the attached footplate 130 in a downward or plantar extensiondirection. Thus, in one configuration, when the footplate is rotated up,in dorsi extension as during a preparation for heel strike, the cableflexes the leaf spring, which exerts a resistive force on the pulley,which will tend to return the foot plate to a level position. Thisstiffens the device during the toe-up, heel-down movement. Flipping theorientation of the leaf spring, the direction of the cable, and theattachment point on the pulley reverses the application of the springforce, creating resistance when the footplate is rotated down. A pair ofleaf springs, arranged on opposite interior walls (i.e., front and backwalls) of the tubular member may be used to provide stiffening duringrotation in both directions.

The embodiment of FIG. 8 includes a vertically moveable pivot 820, whichtranslates vertically within member 105. As with the pivot in the FIG. 7embodiments, locating the pivot closer to the distal end of leaf spring805 makes it stiffer, and locating the pivot closer to the proximal endmakes it stiffer. Pivot 820 may be translated down by an attachedpiston, which is part of hydraulic assembly 825. Hydraulic assembly 825is connected via hydraulic fluid line 835 to a compressible hydraulicbladder 830. When bladder 830 is compressed, hydraulic pressure istransmitted to the hydraulic assembly, which actuates the piston,causing the pivot to translate in a downward vertical direction. Thepivot can be retracted in the vertical direction by the relaxation ofhydraulic pressure, which will occur when bladder 830 is no longercompressed. A non-illustrated spring may be included to assist in thevertical translation of pivot 820.

In operation, when a user applies downward pressure to the footplate130, the bladder is compressed causing the pivot to move downward,shortening the free end of leaf spring 805. This will tend to stiffenthe spring and increase resistance during toe-down movements, like thetransition to terminal stance, right before toe-off. As the foot comesup, the hydraulic pressure drops, and the pivot translates up, weakeningthe spring, which then provides less resistance to two-up movement, asbefore heel strike.

As with FIG. 7 , it is contemplated that the leaf spring orientation andthe position of the pivot can be flipped, and that two assemblies can beprovided, on each of the front and back walls of the member 105 toprovide assistance/resistance in both angular directions.

Throughout this disclosure AFO's have been described in the context ofunilateral devices for one ankle, however, this is not a requirement. Itis contemplated that pairs of devices such those described herein willbe used, one for each ankle of a user, and such devices are squarelywithin the scope of the invention.

Thus far, the present disclosure has been directed to assistive devices,described in reference to exemplary AFOs, which use spring elements tostore energy created by a user's ankle/foot movements during certainstages of the gait. The spring elements then return this stored energyto the user in the form of assistive torque during certain stages of thegait. The springs can be positioned to undergo tensioning at variousdifferent stages of the angular rotation of the pulley/footplate. Thesprings can also be positioned such that they work against each other,to various degrees, at various different stages of the angular rotationof the pulley/footplate. This permits the applied torque curves to betuned to create, for example, softening or stiffening resistance (orweakening or strengthening of assistance) at different stages of theangular rotation of the pulley/footplate. The concepts described thusfar described allow for the design of passive (i.e., non-motorized)devices, and for devices where the role of actuators is limited tochanging the strength of the springs.

In other embodiments, the concepts here before described are applied toactive exoskeletal AFOs. Active AFOs generally use one or moreactuators, such as motors, to apply assistive torque to a joint of theuser during various stages of a gait cycle. These devices may alsoprovide resistive torque. Generally, an active AFO will have a pair ofwearable, battery powered, counter-rotating motors, one for each limb,each motor connected to a pair of force transmitting linkages(preferably Bowden cables). Each pair of Bowden cables is connected to apulley, which is connected to a footplate. When a motor rotates in onedirection, the footplate rotates in a toe-up direction, and when themotor rotates in the opposite direction, the footplate rotates in a toedown direction. This applied assistive torque assists a user withwalking. Again, these devices may be configured to provide resistancerather than assistance. An exemplary powered AFO is described in U.S.Patent Publication No. 20190343710, entitled EXOSKELETON DEVICE, theentirety of which is incorporated herein by reference.

The passive spring-based energy storage concepts outlined above may becombined with a powered exoskeletal AFO, in a parallel configuration, tocombine active (i.e., actuated) and passive (i.e., spring-assisted)components to improve the performance of either component independently.Such devices may use springs having adjustable stiffness, to allow thedevices to be tuned to each user's preferences, needs or body mass. Whenconfigured I parallel to the powered actuation system, the springcomponents can offload motor requirements to result in a lighter weightexoskeleton design, save battery capacity, and/or increase battery life.Additionally, the spring can increase the amount of torque and positivepowered force provided to the user at very low cost and low added mass.

In one embodiment, a powered ankle exoskeleton is provided, whichprovides plantar-flexor and/or dorsi-flexor assistance during walking orrunning. During certain phases of the gait cycle, like stance phase, aparallel leaf spring coupled to the pulley engages (stores and returnselastic energy as the lower-limb naturally dorsi-flexes), which offloadsassistive torque and/or power output requirements from the motor. Thisleaf spring design allows for change in stiffness by changing the leafspring and also a rapidly adjustable pivot point, which changes thespring stiffness without replacement so that it can be customized toeach user, their body mass, or ambulatory condition (e.g., slow walking,fast walking, running). In another embodiment, the exoskeleton is usedto provide resistance during walking or running, and the leaf spring isengaged in an opposite direction (off-loading the required resistivetorque and/or power output from the motor).

One such example incorporating the concepts outlined above is depictedin FIG. 9 . There is shown the lower portion of an AFO 900. The AFO hasan upright (vertical), tubular member 105 such as those described above.A rotational bearing carries a rotational element such as a pulley 125within the interior walls of member 105. The pulley 125 is coupled to afootplate 130. A tensile force transmission mechanism (cable, cord,ribbon, chain, etc.), but preferably a Bowden cable 905, has a distalend that is coupled to one side of pulley 125. In the case thatmechanism 905 is Bowden cable, the sheath may be anchored at an anchorpoint 910 on or near member 105, and near pulley 125. The cable 905 hasa proximal end that is coupled to a non-illustrated actuator such as awearable, battery powered motor operable to pull on the cable, and thenallow the cable to extend again when subject to pulling force. In theexample of FIG. 9 , the motor and cable are operable to provide ankletorque in a plantar-extension, or toe-down direction to provideassistance while working, or to provide dorsi extension resistance. Theembodiment of FIG. 9 also includes spring 915, which in this example isa leaf spring. Spring 915 is mounted to a wall of member 105 at a top orproximal end. Spring 915 is coupled to a tensile force transmittingmechanism 925 (e.g., a cable), at a bottom or distal end. The cablecouples the spring to the pulley. In the configuration as shown, whenthe user rotates footplate in a toe-up direction (e.g., in preparationfor heel strike), spring 915 is tensioned. The stored energy is thenreleased as the spring applies toe-down torque to the pulley/footplateas the user proceeds through mid-stance to toe-off. This providesassistance to that movement, and it reduces the amount of powered torqueassistance needed from the motor for the movement.

The device of FIG. 9 also includes a pivot 920, which may be adjusted interms of its position so that it may contact the leaf spring 915 atvariable positions along its length. The pivot may be slid and securedby the user manually, or it may be moved by an actuator as set forth inthe embodiments above. The positioning of the pivot may be the user'sdecision, or it may be determined automatically, for example, inaccordance with the methods discussed in reference to FIGS. 4-5 . Thepositioning of the pivot varies the length of the free end of the spring915, which adjusts the spring's strength.

While the example of FIG. 9 shows a spring providing parallel assistancefor a single actuated cable for plantar-extension, other configurationsare possible and within the scope of the invention. A device with a pairof actuated cables connected to one or more counter-rotating motorsproviding both dorsi and plantar extension is contemplated. The use ofone or two leaf springs, each for a different rotational direction isalso contemplated. Leaf springs that work against the actuateddirection, to reduce assistance or otherwise tune the response curve arepossible. Any combination or positioning of leaf springs, in combinationwith any combination or positioning of actuated cables is within thescope of this disclosure.

An alternative embodiment of a passive assistive AFO is shown in FIG. 10. The device of FIG. 10 includes a hollow, upright member, again,preferably made of carbon fiber, and a medially projecting userattachment device 115, such as a calf cuff. Inside the member is mounteda vertically arranged leaf spring 1005 (e.g., an elastic carbon fiberbar), which is mounted at a proximal end to an inside wall of member105. Mounting can be done with a stand-off block (“1”), a cover (“3”)and fasteners as illustrated in the magnified portion of the figuredenoted as “B”. The device includes a footplate 130, coupled to a pulley125, which rotates with a rotational bearing mounted through side wallsof the member 105, such that the side surfaces of the pulley are withinthe member side walls. An upper portion of the pulley 125 is removable(the removable section denoted as “4”), and this portion passes in aslot or aperture in the member 105. The upper portion of the pulley 125also passes through a slot or aperture in the leaf spring 1005 atposition 1010. This slot or aperture has a width that clears the widthof the upper portion of the pulley, but does span the entire width ofthe anterior and posterior surfaces of the spring 1005. This will allowfor an interference to occur between stops 1015 (also denoted “5” in B)and the leaf spring, as will be discussed below. The pulley 125 includesa rotational bearing that rotates around axle pin 1020, which is securedby and between medial and lateral walls of the member.

In certain embodiments, the components illustrated in FIG. 10 are partof a powered device, where a pair cables, e.g., Bowden cables, arecoupled to the pulley to provide powered dorsi and plantar extensionassistance. In such cases, these cables will be coupled to anon-illustrated battery powered motor that can provide tension andtherefore rotation and counter rotation to the pulley. In theseembodiments, the device may include a pair of Bowden cable tensioners(as marked in A) to which the sheaths of the Bowden cables are mounted.The tensioners may include barrels that allow the tension between thesheaths to be varied with respect to the inner cables. In active devicesthe footplate 130 may be attached to the pulley 125 via an optionalstrain sensor and mounting block (“8” in B), which may be useful fordata collection and computing desired supplied power ankle torque. Inalternative passive embodiments, the footplate may mount directly to thepulley without an intervening sensor block. Active or passive devicesmay also include other sensors, such as an angle encoder (“6” in B) orother angle position, velocity, or acceleration sensor, and one or morepressure sensors on the footbed.

In the device of FIG. 10 , one or more stop assemblies 1015 may beaffixed to the pulley 125 at a variety of positions along the pulley'sperimeter. In one case, there are a number of fixed positions the stopassemblies can occupy, but alternatively, the stop assemblies could beslid along continuously and fixed at a continuum of positions, using atensioning mechanism. Fixed positions may be preferable because the stopassemblies must resist a large amount of shearing force in operation.The positions of the stop assemblies along the pulley determine theangular position of the pulley at which the leaf spring 1005 is engagedand deflects. Referring now to stop assembly 1015 in A, as the footplatepictured is rotated into a more toe-up position, the leaf spring will beengaged and will store energy, which will be returned as the foot isrotated back down. Another stop assembly on the anterior side of theleaf spring will perform the same function for toe-down rotation. Byadjusting the positions of the stops, the angles at which resistancebegins can be changed.

In alternative embodiments, the device of FIG. 10 may include one ormore adjustable or fixed pivots arranged within the member 105. Thesepivots are arranged between the leaf spring and the interior surfaces ofthe member such that the spring engages the pivot when it deflects inthe direction of the pivot. The pivots can be slid up or down the lengthof the leaf spring, by the user, to change the strength of the springfor a given direction of rotation. A pivot on the anterior side of thespring will stiffen the spring against footplate rotation in a toe-updirection as the pivot moves down. A pivot on the posterior side of thespring will stiffen the spring against footplate rotation in a toe-downdirection as the pivot moves down. Both pivots are independentlyadjustable and fixable by the user.

FIG. 11 shows how the device of FIG. 10 , in one configuration with astop assembly placed as shown, will store and return torque to thepulley/footplate thought the stages of the gait. Here, the stop isplaced on the anterior side of the pulley and engages the spring uponrotation in the dorsi flexion (toe-up) direction. As can be seen, thespring provides increasing resistance and energy storage during thestance. During the mid to late stance push-off phase, the spring returnsthe energy as the foot rotates to level, and the spring is not, or isminimally, engaged as the user rotates the foot forward during the swingphase. In the case of an active assistive device, the prescribedassistive torque during these movements may be represented by the dottedline (“prescribed external torque”). As can be seen, the torque curve ofthe passive spring matches the prescribed torque curve quite well,suggesting that the spring can be helpful in reducing the amount oftorque delivered by the motor of the active device, at all gait stages.An engagement clutch may be used to engage the previously describeddorsi flexion resistance spring at heel strike and release the dorsiflexion resistance spring at toe-off to allow for unresisted dorsiflexion during the swing phase. As depicted, the motor may need to overpower the dorsi flexion resistance spring during swing phase; howeverthere would be a net positive/beneficial effect for the springoffloading the motor across the entire stance phase because the ankle isin greater dorsi flexion during stance phase than during swing phase.

FIGS. 12 and 13 illustrate an alternative assistive device incorporatinga pair of vertically mounted, spaced apart leaf springs, preferablyarranged within the hollow upright member of the device. In thearrangement of FIGS. 12 and 13 a posterior spring 1310 and an anteriorspring 1305 are arranged on posterior and anterior sides of the uprightmember 105. These springs are mounted to the member 105 at theirproximal ends. The device also includes a pair of spring pivots 1315,1320, which may be slid vertically between the interior walls of themember and the springs, and fixed in position, where they will beengaged by their respective spring. This allows a user to set thestrength of each spring, as in the embodiments described above. Arotational hinge element 1340 includes a bearing, which may receive anon-illustrated axle pin, which is secured by and between the medial andlateral walls of the member, as in the embodiment of FIG. 9 . Thus,hinge element 1340 is arranged within the member and rotates withrespect to the member. The hinge element 1340 is coupled to a mountingblock 1335 (e.g., through an aperture in a medial sidewall of themember), which is coupled to a footplate. Again, this permits thefootplate to rotate with respect to the member and the rotational hingeelement.

The rotational hinge element 1340 includes a tab or projection 1325which projects upwardly and is arranged between the distal free ends ofthe leaf springs. When the footplate rotates in a toe-up direction, thetab engages the anterior leaf spring 1310, and when the footplaterotates in a toe-down direction, the tab engages the posterior leafspring 1305. In each of these movements, the spring stores energy, andreturns it as torque to the footplate when it counter-rotates.

In certain embodiments, the tab 1325 is mounted to the bearing portionof the hinge mechanism 1340 via a clamp 1330. The clamp 1330 may beloosened and retightened to allow the user to change the angle betweenthe tab 1325 and the remainder of the hinge mechanism 1340. This allowsangular adjustment to be made between the footplate and the tab, whichallows the user to set the equilibrium angle of the footplate, i.e., theangle at which the footplate rests before further motion in eitherdirection engages either spring.

FIG. 14 shows an alternative arrangement for adjusting the equilibriumangle of the footplate and the spring-engaging tab. In the embodiment ofFIG. 14 , the distal end of member 105 includes a termination cap 1405,which defines a through aperture. The aperture receives anon-illustrated axle pin. A rotational bearing 1415 is secured withinthe cap and rotates around the axle pin. The rotational bearing 1415includes an upwardly extending tap 1420, which extends up between thedistal ends of non-illustrated leaf springs. The rotational bearing 1420has on a medial side teeth, which engage corresponding teeth on an uppertab coupled to the footplate. The footplate tab and the rotationalbearing can be held in tension by non-illustrated one or more fastenerssuch that the two parts rotate with respect to the member together. Thefasteners may be loosened, and the relative positions of the rotationalbearing and the footplate tab can be changed. This has the effect ofchanging the angle of the footplate with respect to the tab, whichallows for the equilibrium angle of the footplate to be adjusted.

The exemplary embodiments described above have been AFO's or orthosesthat provide assistance or resistance to a user's ankle. The personal ofordinary skill will appreciate that the teachings of this disclosure areequally applicable to other joint orthoses such as orthoses for wrists,knees and elbows.

It will be understood by one having ordinary skill in the art thatconstruction of the described invention and other components is notlimited to any specific material. Other exemplary examples of theinvention disclosed herein may be formed from a wide variety ofmaterials unless described otherwise herein.

For purposes of this disclosure, the term “coupled” (in all of itsforms: couple, coupling, coupled, etc.) generally means the joining oftwo components (electrical or mechanical) directly or indirectly to oneanother. Such joining may be stationary in nature or movable in nature.Such joining may be achieved with the two components (electrical ormechanical) and any additional intermediate members being integrallyformed as a single unitary body with one another or with the twocomponents. Such joining may be permanent in nature or may be removableor releasable in nature unless otherwise stated.

Furthermore, any arrangement of components to achieve the samefunctionality is effectively “associated” such that the desiredfunctionality is achieved. Hence, any two components herein combined toachieve a particular functionality can be seen as “associated with” eachother such that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected” or “operablycoupled” to each other to achieve the desired functionality, and any twocomponents capable of being so associated can also be viewed as being“operably couplable” to each other to achieve the desired functionality.Some examples of operably couplable include, but are not limited to,physically mateable, physically interacting components, wirelesslyinteractable, wirelessly interacting components, logically interacting,and/or logically interactable components.

It is also important to note that the construction and arrangement ofthe elements of the invention as shown in the examples are illustrativeonly. Although only a few examples of the present innovations have beendescribed in detail in this disclosure, those skilled in the art whoreview this disclosure will readily appreciate that many modificationsare possible (e.g., variations in sizes, dimensions, structures, shapesand proportions of the various elements, values of parameters, mountingarrangements, use of materials, colors, orientations, etc.) withoutmaterially departing from the novel teachings and advantages of thesubject matter recited. For example, elements shown as integrally formedmay be constructed of multiple parts or elements shown as multiple partsmay be integrally formed, the operation of the interfaces may bereversed or otherwise varied, the length or width of the structuresand/or members or connectors or other elements of the system may bevaried, the nature or number of adjustment positions provided betweenthe elements may be varied. It should be noted that the elements and/orassemblies of the system might be constructed from any of a wide varietyof materials that provide sufficient strength or durability, in any of awide variety of colors, textures, and combinations. Accordingly, allsuch modifications are intended to be included within the scope of thepresent innovations. Other substitutions, modifications, changes, andomissions may be made in the design, operating conditions, andarrangement of the desired and other exemplary examples withoutdeparting from the spirit of the present innovations.

Reference throughout this specification to “one embodiment,” “anembodiment,” or similar language means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment. Thus appearances of the phrase“in one embodiment,” “in an embodiment,” and similar language throughoutthis specification may, but do not necessarily, all refer to the sameembodiment.

The exemplary structures disclosed herein are for illustrative purposesand are not to be construed as limiting. In addition, variations andmodifications can be made on the aforementioned structures withoutdeparting from the concepts of the present invention and such conceptsare intended to be covered by the following claims unless these claimsby their language expressly state otherwise.

The invention claimed is:
 1. A wearable assistive device, comprising: anextended, linear structural member having a first end and a second enddefining a long axis; an attachment device coupled to the linearstructural member and extending medially from the member, the attachmentdevice configured to secure the member to a limb of a user; a rotationalbearing disposed within the linear structural member and positioned onthe long axis near the second end of the linear structural member; afootplate dimensioned to support a foot of a wearer of the assistivedevice and coupled to the rotational bearing such that it may rotateabout an axis of rotation that is orthogonal to the long axis of thelinear structural member; a first leaf spring attached to the linearstructural member, the leaf spring having a long axis extending parallelto the long axis of the linear structural member; and an engagementmechanism coupling the footplate to the first leaf spring, theengagement mechanism arranged and configured to engage and deflect theleaf spring when the footplate rotates beyond a predetermined rotationalposition in a first direction.
 2. The device of claim 1, wherein thelinear structural member is tubular having a closed circumferentialcross section, and wherein the first leaf spring is arranged in aninterior of the structural member.
 3. The device of claim 2, wherein thefirst leaf spring has a first end and a second end and is anchored to afirst interior wall of the tubular member at its first end, and whereinthe device includes a pivot that is arranged within the tubular memberbetween the leaf spring and a second interior wall of the tubularmember, the pivot arranged to contact the leaf spring when the secondend of the leaf spring is deflected away from the first interior wall,such that the leaf spring deflects around the pivot.
 4. The device ofclaim 3, wherein the pivot is vertically translatable within the tubularmember, and may be positioned to vary a stiffness of the first leafspring.
 5. The device of claim 4, wherein the pivot is anchored to anupper end of the tubular member by a spring, which, upon extension,exerts an upward force on the pivot.
 6. The device of claim 5, whereinthe pivot and spring are configured such that the pivot may translatedownward upon deacceleration of the device as it is moving in a downwardvertical direction.
 7. The device of claim 4, wherein the pivot istranslatable by an electronically controlled pivot actuator.
 8. Thedevice of claim 7, wherein the device includes one or more sensorsmeasuring data regarding user interaction with the device, the one ormore sensors being selected from the group of: an angular position,velocity and acceleration sensor associated with the rotational bearing,and a pressure sensor located on the footplate configured to measurepressure exerted by the user's foot onto the footplate, and wherein thepivot actuator is electronically controlled with a controller totranslate the pivot as a function of the data measured by the one ormore sensors.
 9. The device of claim 1, further including a bearingactuator coupled to a cable coupled to provide rotational force to therotational bearing, wherein the leaf spring and the engagement mechanismare arranged such that, when deflected, the leaf spring exertsrotational force to the footplate that assists the actuator in rotatingthe footplate in either the first or second direction, the seconddirection being an opposite rotational direction from the firstdirection.
 10. The device of claim 1, wherein the footplate is coupledto the rotational bearing by a pulley, and wherein the engagementmechanism is a cable coupling the pulley to the leaf spring.
 11. Thedevice of claim 1, wherein the linear structural member is tubular, andwherein the leaf spring is arranged on an exterior surface of thestructural member.
 12. The device of claim 11, wherein the leaf springhas a first end and a second end and is anchored to the exterior surfaceof the tubular member at its first end, and wherein the device includesa pivot that is arranged between the leaf spring and the exteriorsurface of the tubular member, the pivot arranged to contact the leafspring when the second end of the leaf spring is deflected toward thetubular member.
 13. The device of claim 12, wherein the pivot isvertically translatable along a vertical length of the tubular member.14. The device of claim 1, further comprising a second leaf springattached to the linear structural member, the second leaf spring havinga long axis extending parallel to the long axis of the linear structuralmember, wherein the engagement mechanism is arranged and configured toengage and deflect the second leaf spring when the footplate rotatesbeyond a predetermined rotational position in a second direction, andsecond direction being an opposite rotational direction of the firstdirection.
 15. The device of claim 14, wherein the first and second leafsprings have different stiffnesses.
 16. A wearable assistive device,comprising: an extended, linear structural member having a first end anda second end defining a long axis through a center of the linearstructural member; an attachment device coupled to the member andextending medially from the member, the attachment device configured tosecure the member to a limb of a user; a rotational bearing disposedwithin the linear structural member and positioned on the long axis nearthe second end of the linear structural member; a footplate dimensionedto support a foot of a wearer of the assistive device and coupled to therotational bearing such that it may rotate about an axis of rotationthat is orthogonal to the long axis of the linear structural member; atleast one leaf spring attached to the linear structural member, the leafspring having a long axis extending parallel to the long axis of thelinear structural member; and a pulley coupling the footplate to theleaf spring, the pully that carries a first stop that engages anddeflects the leaf spring when the footplate rotates beyond apredetermined rotational position in a first direction.
 17. The deviceof claim 16, wherein the pulley carries a second stop that engages anddeflects the leaf spring when the footplate rotates beyond apredetermined rotational position in a second direction, the seconddirection being opposite of the first direction.
 18. The device of claim16, wherein the extended, linear structural member is tubular, having aclosed circumferential cross section, and wherein the pulley includes anaccurate section that passes through one or more apertures in an outsidewall of the tubular linear structural member.
 19. A wearable assistivedevice, comprising: an extended, linear structural member having a firstend and a second end defining a long axis through a center of the linearstructural member; an attachment device coupled to the member andextending medially from the member, the attachment device configured tosecure the member to a limb of a user; a rotational bearing disposedwithin the linear structural member and positioned on the long axis nearthe second end of the linear structural member; a footplate dimensionedto support a foot of a wearer of the assistive device and coupled to therotational bearing such that it may rotate about an axis of rotationthat is orthogonal to the long axis of the linear structural member; afirst leaf spring attached to the linear structural member, the leafspring having a long axis extending parallel to the long axis of thelinear structural member; and wherein the rotational bearing is coupledto a tab arranged to engage and deflect the first leaf spring when thefootplate rotates beyond a predetermined rotational position in a firstdirection.
 20. The device of claim 19, wherein the tab is rotationallyadjustable about an axis of rotation of the rotational bearing and maybe reversibly fixed to the rotational bearing such that an orientationof the tab may be adjusted relative to a plane of the footplate.
 21. Thedevice of claim 19, further comprising a second leaf spring, wherein therotational bearing is coupled to a tab arranged to engage and deflectthe second leaf spring when the footplate rotates beyond a predeterminedrotational position in a second direction, the second direction beingopposite the first direction.
 22. The device of claim 21, wherein theextended, linear structural member is a tubular member having a closedcircumferential cross section, and wherein both the first and secondleaf springs are arranged in an interior of the tubular structuralmember.
 23. The device of claim 19, further comprising at least onetranslatable pivot arranged between a wall of the linear structuralmember and the first leaf spring such that a lower end of the leafspring deflects around the pivot when it is engaged and deflected by thetab.
 24. The device of claim 23, wherein the linear structural member isa tubular member having a closed circumferential cross section, andwherein the at least one translatable pivot is arranged between aninterior wall of the linear structural member and the first leaf spring.25. The device of claim 19, wherein the at least one translatable pivotis anchored to an upper end of the linear structural member by a spring,which, upon extension, exerts an upward force on the pivot.
 26. Thedevice of claim 25, wherein the pivot and spring are configured suchthat the pivot may translate downward upon deacceleration of the deviceas it is moving in a downward vertical direction.
 27. The device ofclaim 23, wherein the pivot is translatable by an electronicallycontrolled pivot actuator.
 28. The device of claim 27, wherein thedevice includes one or more sensors measuring data regarding userinteraction with the device, the one or more sensors being selected fromthe group of: an angular position, velocity and acceleration sensorassociated with the rotational bearing, and a pressure sensor located onthe footplate configured to measure pressure exerted by the user's footonto the footplate, and wherein the pivot actuator is electronicallycontrolled with a controller to translate the pivot as a function of thedata measured by the one or more sensors.
 29. The device of claim 19,further including a bearing actuator coupled to a cable coupled toprovide rotational force to the rotational bearing, wherein the leafspring and the tab are arranged such that, when deflected, the leafspring exerts rotational force on the footplate that assists the bearingactuator in rotating the footplate in either the first or seconddirection, the second direction being an opposite rotational directionfrom the first direction.